Means for synchronizing telegraphic and other apparatus.



L. M. POTTS. I

MEANS FOR SYNCHRONIZING TELEGRAPHIC AND OTHER APPARATUS.

v v APPLICATION FILED APR-30.1913- 1,201.,21. Patented 00. 17,1916,

2 SHEETS-SHEET 1.

L. M. POTTS. MEANS FOR SYNCHRONIZING TELEGRAPHIC AND OTHER APPARATUS.

APPLICATION FILED APR. 30 19:3-

2 SHEETS-SHEET 2.

TED STA LOUIS MAXWELL POTTS, OF BALTIMORE, MARYLAND, ASSIGNOR TO AUSTIN MoLANAI-IAN, OF BALTIMORE, MARYLAND.

MEANS FOR SYNCI-IRONIZING TELEGRAPHIC AND OTHER APPARATUS.

Specification of Letters Patent.

Patented Oct. 1'7, 1916.

Application filed April 30, 1913. Serial No. 764,660.

To all whom it may concern:

Be it known that I, -LoI7is MAxwELL Form, a citizen of the United States, residing in Baltimore city, and State of Maryland, have invented certain new and useful Improvements in Means for Synchronizing Telegraphic and other Apparatus, of which the following is a specification.

The primary object ofthis invention is to provide improved means for effecting and maintaining synchronous motion between moving parts located at a distance from each other, as for example, between transmitting and receiving apparatus in telegraph or other signaling systems where the same current which transmits the signals over the line also acts primarily to control the synchronism. In such systems as the Rowland, for example, this signaling and synchronizing current is subjected on the transmission of each signal to certain alterations or modification ot' its normal form, and when the number of modified impulses to the normal impulses exceeds a given amount, the regulating quality of the current becomes impaired and the synchronism less accurate.

Take the case wherethe normal current on theline is an alternating current, and the signals formed by reversing the impulses in certain combinations, this will not materially affect the synchronism of apparatus .primarily controlled by this current, in which the synchronism is regulated, for example, as described in U. S. Patent No. 726,750, as long as the proportion of the reversed impulses to the normal is less than fifty per cent, but this places a limitation on the number of signals which may be transmitted with a given signaling current. For example, suppose for each signal eight impulses are allotted. In such a case combinations of one, or two, or three impulses may be effected in each group of eight impulses to form the signals, but signals of combinations of four or more impulses cannot be formed without affecting the synchronism. Even when less than 50% are reversed there is a slight shift of the phase.

According to my present invention, the reversing or modifying of the impulses to form the signals does not affect the synchronism, so that combinationsinvolving as many as seven impulses in a group of eight maybe modified without impairing the synchronism, and this is a great advantage, since it permits of the utilization of a much greater number of the impulses for signalin". I accomplish this in one way by the improved means which I shall now describe in detail, reference being had to the accompanying drawings, wherein,

Figure 1, is a diagram of circuits in the apparatus embodying one form of my invention, and Fig. 2, a diagram illustrating the character of the synchronizing currents under' various conditions.

Referring to the drawings, 1 and 2 indicate two direct current dynamos which constitute the source of the line signaling and synchronizing current. These dynamos are so connected as to deliver positive currentuto conductor 3, and negative current to conductor 11, while "their other terminals are connected to earth by a common conductor 5. Tapped on to the conductors 3 and 1, are a series of pairs of stationary contacts 6 and 7, between each pair of which is adapted to move a contact 8. Each of the contacts 8 is connected to a separate segment of a transmitting commutator or sunflower 9, over which travels a brush 10, driven in any suitable way by direct current motor 11, receiving its current from local supply mains 12 and 13. Current is transmitted to line 11, from commutator 9, through a collector ring 15, over which travels brush 16, permanently electrically connected to brush 10, and also driven by motor 11. The movable contacts 8 normally rest against corresponding contacts 7, but these contacts are connected, as

shown, alternately to opposite poles of the' dynamos land 2, as are also the contacts 6, so that as long as movable contacts 8 are all in engagement with contacts 7, impulses of alternate polarity will be transmitted to line through the commutator 9, as the brush 1O sweeps over successive segments of this commutator, which current will take the,

l ent.

, rent motor 21.

nations. This contact is for the purpose of operating a lamp, bell or other signal at the receiving station. Nothing new, however, is herein claimed for this system of transmission. It is merely shown as a part of a system in which my invention may be used. So far as the rest of the apparatus, shown at the transmitting end of theline is concerned, we may {disregard this for the pres As for the operation of contacts 8, this may be effected by any suitable transmitting mechanism. Current from the transmitting sunflower 915 is transmitted over line 14 to a corresponding sunflowerdevice at a receiving station, the latter device comprising a collector ring 17, permanently connected to line, a commutator 18 having a number of insulated segments corresponding to those of a transmitting sunflower, I brushes 19 and 20, adapted to sweep over the and two electrically connected commutator 18 and collector ring 17, respectively, and both driven by a direct cur- The segments of commutator 18 are connected respectively through the :coils of nine receiving relays 22, to a common conductor 23, in series with the coils of a synchronizing polarized relay 24, and the earth, as shown. Eight of these relays are for the regular signals, while the ninth is for the purpose of operating the lamp, bell or other extra SIgTIiTlTHg' dQXdCQ referred to -imconnection with contacts 8. This much of the apparatus is in itself also old.

The motor 21 drives the brush 19 in synchronism with the brush 10, so that the successive relays 22 receive the impulses transmitted to line through the successive contacts 8. So long as these impulses are in the normal direction, theserelays will not be affected; that is to say, their tongues will all remain against the back stop contacts, but whenever a reversed impulse traverses one of these relays, its tongue will be sent against its forward contact. Therefore, the relays 22 are operated in combinations de-' pending upon the combinations of contacts 8 operated. These relays 22 may, therefore, be employed to operate printing or other receiving apparatus, but such mechanism forms no part of my present invention, nor is a description thereof necessary to an understanding of said invention.

While each relay 22 receives only those impulses distributed to it by the commutator 9, the relay 24: receives every line impulse, and acts primarily to regulate the synchronism of the motor 21 in the following way: One of the brushes of this motor is connected by conductor 25, to collector ring 26, associated with a synchronizing commutator 27 made up of a plurality of segments double in number those of the receiving commutator 18. The collector ring 26, and commutator 27, are swept by electrically connected brushes 28 and 29, driven by the motor 21. Alternate segments of the commutator 27 are connected respectively to two conductors 30 and 31, which are in turn electrically connected to two stationary contacts 32 and 33, adapted to be engaged alternately by a vibrating reed 31, made fast at one end to a suitable support 35, and carrying at its other end an armature 36, which moves in front of a magnet 37. I preferably provide the reed with a stationary stop 33 so that when the magnet 37 becomes dee'nergized the reed always starts from exactly the same phase position, the contacts 32 and'33 being in practice yielding to make certain contact. The reed 34 is in permanent electrical connection through support 35 and conductor 35 with the negative supply main 39.

Connected in circuit between wire joint 38, of conductor 25, and the negative main of the local supply mains and 40, is a resistance 41, which acts in conjunction with the vibrating reed 34 and commutator 27, to regulate the speed of the motor 21, as will 'now be described.

For the present purpose, we may regard the reed 34; as any body making contact alternately with contacts 32 and 33, at a rate bearing a fixed relation to the period of the line current. Then, if the reed 34 is against either of its contacts 32, 33 while brush 28 is passing over any of the segments of the commutator 27 connected to the contact with which the reed is at that time engaging, it will be seen that the resistance 41 "will be short circuited; while if the reed is engaging either of the said contacts at the same time that the brush 28 is passing over any of the segments of commutator 27 connected to the oppositereed contact that is, the one which the reed is not at that time engaging, the resistance 41 will be in series with the armature of motor 21. In one case the motor will receive much greater current than in the other.

Consider any case in which the vibrations of the reed and rotation of the brush arm have some phase relation between the above two. If any relation between the first tWo mentioned is continuously maintained, it will be readily seen that at rapidly recurring intervals the resistance 41 will be in circuit and out of circuit with the motor 21. Depending upon the relation between the vibration of the reed and the rotation of the brush 28, the intervals during which this resistance 41 is in circuit and out of circuit with the motor armature will vary in length and in addition to the regular current flowing through the armature, there will be a pulsating current flowing through the same, and the strength of these impulses will depend upon the relation existing between the vibrations of the reed 34 and the rotation of brush 28. Consequently, while the reed is vibrating in unison with the rotation of the brush, there can be various amounts of current flowing through the armature ofthe motor, depending upon the relation of the reed and the brush 28.

If the rate of vibration of the relay tongue increases, the relation between the vibration of the reed and the rotation of the brush will change, but in such a manner as to strengthen the impulses flowing through the motor armature; and consequently the speed of the motor will be increased, but only until this speed corresponds to the rate of vibration of the reed. If the armature of the motor attempts to go faster than the vibrations of the reed, the impulses through the armature are weakened and the speed is kept normal. If the motor attempts to go slower, the impulses are-strengthened, and the speed of the motor is still kept normal. Consequently, the speed of the motor follows any changes in the vibrations of the reed, and any tendency for the motor to change its speed, as, for instance, a change in the voltage inthe power circuit, is immediately compensated for by a slight shift in the phase difference above mentioned.

The motor may be provided with a damper 21 of the kind shown and described in U. S. patent to Henry A Rowland, No. 713,497, or other suitable means for steadying its motion or reducing pumping. Such damper, in the case shown, comprises a closed casing mounted fast in the motor shaft and containing mercury or other suitable damping liquid.

The method of regulating the speed of motor 21, above described, barring the reed 34 and damper 21 is substantially the same as that set forth in U. S. Patent No. 7 26,7 50.

If the reed 34 were replaced by relay 24; that is, if we substitute for the blade of the reed, the tongue of the relay 24, in which event the segments in commutator 27 would correspond in number to those of commutator 18, the resultant effect on the motor 21 would be substantially the same as long as the line current continues to reverse regularly; that is, as long as no signals are transmitted which modify the normal line impulses received by the relay 24, and even when these do not amount to fifty per cent. of the impulses transmitted, the synchronism is not appreciably affected, but when this amount is exceeded, the regularity of the vibration of the tongue of relay 24 would become affected to such an extent as to interfere with the regulation of the motor.

This is overcome in the present case by the reed 34 and associated parts which will now be described in greater detail.

'One of the coil terminals of the reed magnet 37 ispermanently connected by conductor 42 to the tongue of relay 24, while the other of said terminals is connected by conductor 43- intermediate of two condensers 44 a and 45, bridged acrosstwo conductors 46 and 47, from-the supply mains 39 and 40,

and these conductors are connected respec-- tively through resistances 48 and 49 to the tongue contacts 24 and 24 of the polarized relay 24.

The natural period of the reed 34 is twice that of the line current and for this reason there are twice as many segments in commutator 27 as in commutator 18. Y I

First assume the case when the dynamos are delivering to line an alternating current without signals being transmitted. The tongue of polar relay 24 willthen vibrate uninterruptedly between its contacts in unisonwith the impulses ofthis current. \Vhen its tongue is against contact 24*, condenser 44 discharges and condenser 45 charges,

sending an impulse to the magnet of the reed 34, and when the tongue of relay 24 is against contact 24, condenser 44 charges and condenser 45 discharges, thus sending another impulse through the coils of magnet 37. Therefore, on each reversal of the line current the reed magnet 37 receives an operating impulse. These impulses are indicated by the series CD, Fig. 2. Each succeeding impulse is of different polarity, since one represents the charged current and the other the discharge current of a condenser.

It is a well known principle in the theory of sound that if any body having a fixed natural periodof vibration-be acted upon by a periodicv force varying .slightly from its natural period, that such body will vibrate in synchronism with the applied force. The reed 34 will therefore vibrate in synchronism with the regular alternations of the line current by virtue of the regulating force constituting the impulses which pass through its magnet coils.

Now suppose a signal is transmitted, which i we will assume is elfected by reversing the direction of the third impulse from the left in the series A-B, Fig. 2. The current will then. be as indicated by the diagram E-F, Fig. 2. When this takes place the tongue of polar relay 24 will remain against the con- 7 tact to which it was drivenby the next preceding impulse until an impulse comes along of reverse polarity. In other words, itwill remain against said contact for the period of three impulses. During this-time the reed magnet 37 receives but one impulse, the second one on the left of the series GH,

Fig. 2, the two succeeding impulses shown in I tacts operated by the reed. The next succeeding line reversal will give it another impulse, and start it at its original amplitude and also correct its phase by the amount it has gotten out. It is only necessary that the line reversals come sufficiently often, so that the reed does not get out of phase too much for the impulse to correct it. The maximum difference possible without loss of svuchronism is actually between 90 and 180.

A weight 36 on the end of the reed 34L acts to keep up the amplitude of the reed longer when magnet coil 37 is receiving no impulses.

The interval between the succeeding reversals of the line current, even when a great many are omitted, is short in comparison to the natural period of the rotating elements of the distributing commutators driven by motors 21 on account of the steadying action of the mercury damper 21 and the heavy armature of the motor. The distributers therefore do not follow these slight changes of phase of the reed when impulses are modilied, but remains substantially the same independent of such phase changes at short intervals, so that the synchronism of the commutator brush 19 is almost absolutely dead beat and retains a fixed phase relation.

Inasmuch as magnet 37 receives one impulse on each reversal of the line current, and since these impulses should act on the magnet only in one phase of the movement of the reed, approximately in the out position, for example, the reed in the case shown must vibrate at twice the period of the line current. If the magnet 37 received these impulses at the out position, as well as the in position of the reed, this would kill the effect of the magnet. The reed is, however, started into vibration by the reversal of the line current. I

The period of the line current depends upon the speed of motor 11, and in cases where the voltage of the driving current of this motor does not fluctuate materially, it will not be necessary to provide'this motor with any extraneous speed governing means; but when the motor is supplied with current from a commercial circuit, it will be advisable to provide such regulating means, in which event, l preferably employ an arrangement similar to that for governing the motor 21, barring the relay 2:: and associated parts.

Tn the case shown the apparatus for governing the speed of motor 11 comprises a vibrating reed 50, magnet 51, contacts 52, 53 and 54, a synchronizing commutator 55, collector ring and brushes 5'? and 58 driven by motor 11, and a synchronizing resistance 59, all said parts being duplicates of corresponding parts at the receiving end of the line and operating in the same way except that the magnet of reed 50 is subject to impulses through contact 51. The resistance 60 is merely for regulating the current through magnet 51. The reeds 3-1 and 50 have precisely the same natural period.

The motors l1 and 21 may be provided with rheostats (31 and (32, but these are not essential, especially when the motors are designed to run at the-same speed for a given voltage.

iVhile I have herein shown and described but one specific embodiment of my said invention, it should be understood that I do not limit the scope of my invention to such specific disclosure. The tuning fork or reed, for example, may be replaced by some other element having a fixed natural period of motion, and various other changes effected without departing from the true spirit of my invention.

lVhat I claim isz- 1. The combination with an elcctric circuit including means to impress thereon electrical impulses alternating in polarity, of an element having a fixed natural period of motion, and means controlled by the reversals of the current in said circuit to force the movement of said element.

2. The combination with an electric circuit including means to impress electrical impulses thereon alternating in polarity, of an element having a fixed natural period of motion, and means controlled by the reversals of the current in said circuit to impart forced oscillations to said element after the same has started into motion.

3. The combination with an electric circuit including means'to impress thereon electrical impulses alternating in polarity, of an element havinga fixed natural period of motion, and means controlled by the reversals of the current in said circuit to give impulses to said element to maintain its periodic motion and also to bring its motion into phase with the reversals of said current.

The combination with an electric circuit including means to impress thereon electrical impulses alternating in polarity, of

an element having a fixed natural period of motion, and means controlled by the reversals of the current in said circuit to start said element in motion and impart forced vibrations thereto to maintain its motion in phase'with the reversal in polarity of said impulses.

5. The combination with an electric circuit including means to impress thereon electrical impulses alternating in polarity, of an element having a fixed natural period of motion, a polarized relay controlled by the reversals of the current in said circuit, a magnet adapted to give impulses to said element to maintain its periodic motion and also to bring its motion into phase with the reversals of said current, and means controlled by said relay to impart an energizing current to said magnet on each reversal of the current in said circuit.

6. The combination with an electric circuit including means to impress thereon electrical impulses alternating in polarity, of an element having a fixed natural period of motion, a polarized relay controlled by the reversals of the current in said circuit, a magnet adapted to force the motion of said element, and means comprising condensers and a source of current controlled by said polar relay to impart an energizing impulse to said magnet on each reversal of the current in said circuit.

7. The combination with an electric circuit including means to impress electrical impulses thereon alternating in polarity, of a tuning fork or reed, and means controlled by the reversals of the current in said circuit to impart forced oscillations to said reed after the same has started into motion.

8. Thecombination with an electric cir- -cuit including means to impress thereon electrical impulses alternating in polarity, of a tuning fork or reed, and means controlled by the reversals of the current in said circuit to give impulses to said reed to maintain its periodic motion and also to bring its motion into phase with the reversals of said current.

9. The combination with an electric circuit including means to impress electrical signaling impulses thereon, of a member having a fixed natural period of motion, means controlled by said impulses to syn chronize said member, selecting means, a sunflower device distributing said impulses -to said selecting means, and means controlled by said member to synchronize said sunflower device.

10. The combination with an electric circuit including means to impress electrical signaling impulses thereon, of a tuning fork or reed, means controlled by said impulses to synchronize said reed, selecting means, a sunflower device distributing said impulses to said selecting-means, and .means controlled by said reed to synchronize said sunflower device.

11. The combination with an electric circuit including means to impress electrical impulses thereon alternating in polarity, of means to modify said impulses to form signals, a sunflower device to distribute said impulses, a member having a fixed natural period of motion, means to synchronize sa1d sunflower device to said member, and means controlled by said impulses to synchronize said member to said impulses.

or more of said impulses in combinations to form the signals, of an element having a fixed natural period of motion, and means controlled by the reversals of the current in said circuit to force the movement of said element, the said element continuing its motion naturally and freely during such periods of no reversal ofthe impulses.

14. The combination with an electric circuit, including means to impress electrical impulses thereon, alternating in polarity, of a member having a fixed period of natural motion such that said member shall invariably be in substantially the same phase position at succeeding reversals of the current, and means to synchronize said member with said impulses.

15. The combination with an electric circuit including means to impress electrical impulses thereon, of an element having a fixed natural period of motion, a relay controlled by said impulses, means controlled by said relay to generate electrical impulses the duration of which is independent of that of the first mentioned impulses, and means controlled by said generated impulses to control the phase of said element with respect to the phase of the first mentioned impulses.

16. The combination with an electric circuit, including means to impress electrical impulses thereon alternating in polarity, of a member having a fixed period of natural motion such that said member shall invariably be in substantially the same phase position at succeeding reversals of the current, means to generate electrical impulses from said reversals, and means operated by said generated impulses to synchronize said member with said first mentioned impulses.

In testimony whereof I afiix my signature in presence of two witnesses.

, LOUIS MAXWELL POTTS.

Witnesses:

WALTER H. BILLINGSLEA, JOHN R. Hoornn. 

